Use tighter typing in editing: SimplifyMarkupCommand & TextIterator

Source/core/editing/TextInsertionBaseCommand.cpp

 /*
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 55 matching lines @@
             RefPtrWillBeRawPtr<BeforeTextInsertedEvent> evt = BeforeTextInsertedEvent::create(text);
             startNode->rootEditableElement()->dispatchEvent(evt, IGNORE_EXCEPTION);
             newText = evt->text();
         }
     }
     return newText;
 }
 
 bool canAppendNewLineFeedToSelection(const VisibleSelection& selection)
 {
-    Node* node = selection.rootEditableElement();
-    if (!node)
+    Element* element = selection.rootEditableElement();
+    if (!element)
         return false;
 
     RefPtrWillBeRawPtr<BeforeTextInsertedEvent> event = BeforeTextInsertedEvent::create(String("\n"));
-    node->dispatchEvent(event, IGNORE_EXCEPTION);
+    element->dispatchEvent(event, IGNORE_EXCEPTION);
     return event->text().length();
 }
 
 }